Substrates such as plastics, glass, timber or paper are used for various purposes. However, warpage occurs in these substrates as the areas get bigger. Also, at first it had excellent flatness as the solid line of FIG. 1, but warpage may be generated as time goes by as the thick solid line of FIG. 1, and warpage maybe occurs when the surface of a substrate is coated with functional substances for providing functionality. Such substrate warpage may cause the malfunction of a device and also deteriorate its appearance thereby decreasing the overall product usefulness.
Previously, in order to prevent substrate warpage, a supporting fixture was installed on the substrate or a separate substrate of which the warpage is less was attached to the surface of the substrate, but lots of efforts were needed for most applications. Therefore, researches for preventing substrate warpage by a simple method such as coating are urgently in need.